Anchor bolts, sometimes also referred to as expansion bolts, the terms being used interchangeably herein, are bolts that have a threaded shank whose tip is fashioned to expand outwards when screwed into a hole. By torquing the anchor bolt sufficiently, the expanded end grips the inner circumference of the hole strongly enough to anchor even heavy objects to a wall or ceiling.
In general, the anchor bolt is simply inserted in a hole whose diameter is slightly larger than the nominal diameter of the anchor bolt shank. The anchor bolt is tightened and expands, thereby gripping the hole.